Night Ambulatory Monitoring Of Blood Pressure

Elevated Blood Pressure (BP) is a chronic medical condition with a prevalence of about 45% in the middle-aged population.

The particular interest of this project is given to the diagnosis and treatment of so-called nocturnal hypertension. Unfortunately, current monitoring practice relies on the use of occlusive pneumatic cuffs inflated around the arm to assess BP. Based on oscillometric technique, occlusive cuffs perform intermittent BP measurements every 20 minutes, thus providing only a limited view of the BP regulation landscape. In addition, oscillometric measurement performs a full occlusion of the measured arm inducing awakening reactions, and leading to non-representative overestimated BP values. The non-occlusive measurement of BP is thus an unsolved problem of modern medicine.

The aim of the NAMBP (Night Ambulatory Monitoring of Blood Pressure) project is to develop, implement and test in clinical trials a first-ever non-occlusive BP sensor to be used during sleep.

A novel technology for the non-occlusive measurement of BP from photoplethysmographic (optical) signals, known as Pulse Wave Analysis (PWA), has been investigated for the past decade by the Centre Suisse d'Electronique et de Microtechnique (CSEM, Neuchâtel, Switzerland). The herein proposed system - the CSEM Pulse Watch - consists in a single sensor (watch-like device) attached at the wrist that measures photoplethysmographic waveforms induced by the pulsatility of the skin arteries of the wrist. These waveforms are then post-processed via PWA: The system will detect features in the measured waveforms that correlate, through the phenomenon of wave reflections, to the underlying BP of the patient.

Inclusion criteria

• Patients > 18y
• Good understanding of written and oral German
• Signed informed consent
• Scheduled for 24h blood pressure exam

Exclusion criteria

• Patients with unhealthy mental state
• Patients with an active implantable medical device (AIMD)
• Arteriopathy of the upper limbs with/without stenosis
• Severe congestive heart failure (LV-EF ≤25%)
• Sever aortic-valve stenosis mean gradient >40mmHg, valve area <1cm2)
• Congenital heart disease including aortic isthmus stenosis
• Untreated heart rhythm disorders, heart rate at rest > 120/bpm
• Severe untreated arterial hypertension (BPsyst > 180mmHg, BPdiast > 100mmHg)
• Atrial fibrillation
• Instable angina pectoris
• Malcompliance concerning medication intake
• Active alcohol or drug abuse
• Pregnancy or lactation (women of childbearing age will be asked to performed urinary pregnancy test before the screening phase)